England's Nick Matthew moves into his fifth successive month as world number one, according to the May Dunlop PSA Men's World Squash Rankings published by the Professional Squash Association.
The world champion from Sheffield heads an unchanged top ten, with Egyptian rival Ramy Ashour at No2; fellow Egyptian Karim Darwish - winner of April's Kolkata International in India - in third place; and England's James Willstrop at No4.
Egypt's Wael El Hindi moves up three places to No16 following his successful campaign in last month's Berkshire Open in the USA where the New York-based 30-year-old picked up his eighth PSA World Tour title.
Fellow Egyptian Omar Mosaad also moves up in the May list after marking his 14th Tour final appearance in the Kolkata International. The 23-year-old from Cairo rises a single place to No16.
England's Tom Richards celebrates a career-high world No25 ranking after his surprise unseeded appearance in the Berkshire Open final.
Success in April's Hibiscus Gardens Open in Australia has also led South African Stephen Coppinger to his career-best ranking. The 26-year-old from Cape Town, who also won the Finnish Open in February, moves up to No35.
May 2011 top 20 (inc. points average):
1 [1] Nick Matthew ENG 1,568
2 [2] Ramy Ashour EGY 1,296
3 [3] Karim Darwish EGY 1,022
4 [4] James Willstrop ENG 897
5 [5] Amr Shabana EGY 832
6 [6] Gregory Gaultier FRA 747
7 [7] Peter Barker ENG 618
8 [8] Thierry Lincou FRA 557
9 [9] Mohamed El Shorbagy EGY 470
10 [10] Mohd Azlan Iskandar MAS 434
11 [11] David Palmer AUS 409
12 [12] Daryl Selby ENG 384
13 [16] Wael El Hindi EGY 378
14 [14] Hisham Mohd Ashour EGY 358
15 [13] Laurens Jan Anjema NED 357
16 [17] Omar Mosaad EGY 342
17 [15] Cameron Pilley AUS 330
18 [18] Adrian Grant ENG 295
19 [19] Alister Walker ENG 268
20 [20] Stewart Boswell AUS 255
For full list - see www.psa-squash.com